The synaptology of specific functional classes of vertebrate retinal neurons will be studied in the context of the neurotransmitter contents, neurotransmitter release properties and neurochemical sensitivities of those cells. The model systems selected are the golfish, because it has served as a successful example of a color-coding retina, and the cat, because it may represent a standard mammalian retinal format. I propose to (1) identify the neurochemical categories of interneurons and throughput neurons that are responsible for certain classes of functional operations; (2) characterize synaptic "cascades" of neurotransmitters which chain together and modulate responses of various neurons: (3) map the distributions of post-synaptic receptor molecules on the surfaces of retinal neurons; and (4) map the ontogenies of specific neurochemical classes of neurons in developing fishes and cats. It is possible to study such events by incubating isolated retinas or retinal pieces in media containing radiolabeled substrates for uptake, release and receptor binding studies, and observing light-or neurochemically-evoked alterations in the efficacies of uptake, release or binding via light and electron microscope autoradiography. The developmental studies will center on identifying the times of origin, migrations and metamorphoses of functionally and structurally characterized retinal neurons. Isolated retinas will be incubated in small volumes of media containing radiolabled substrates for uptake and release or for binding. Uptake and release modulation will be attempted with photic and neurochemical stimulation. Localization of receptor molecules will also be attempted with dissociated retinal cells.